Telephone-exchange system



Aug. 25, 1925. 1,550,783

- E. H. CLARK TELEPHONE EXCHANGE sys'ram Filed Oct. l7. 1925 Patented Aug. 215, 1925.

EDGAR H. CLARK, OF RICHMOND HILL, NEW YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEVT YORK.

TELEPHONE-EXCHANGE SYSTEMT.

Application filed October 17, 1923.

T 0 all whom it may concern:

Be it known that I, EDGAR H. CLARK, a citizen of the United States of America, residing at Richmond Hill, in the county of Queens and State of New York, have invented certain new and useful Improvements in Telephone-EXchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to electrical switching devices and more particularly to devices of the character employed in telephone eX- change systems.

The object of the invention is to improve electrical switching devices by preventing an operating bar from being again taken into use before it has fully restored from a previous use.

A feature of the invention relates to the provision, in a switch having contact operating bars actuated by magnets, of means to prevent the re-operation of the magnet until the bar which it controls has completely restored to normal.

Other features will appear from the following description and appended claims.

The invention which is disclosed in a single sheet of drawing is embodied in a line switch of the coordinate type. The switch 102 in which calling subscribers lines terminate comprises a number of groups of horizontal link circuits which serve to interconnect the incoming subscribers lines and outgoing trunks. The links 107 and 108 are a part of one of these horizontal groups, while links 109 and 110 are a part of a second horizontal group. As many other groups of links may be employed as is necessary.

The subscribers lines incoming to the office appear in the switch 102 in vertical rows of contacts 103, 104, etc. For instance, the line 100 appears in the row 103 and has access to all of the links in the group con taining the links 107 and 108. Another line 101 in the same vertical row 103 has access to a second group of links containing the links 109 and 110. A second vertical row 104 is illustrated.

lVith respect to the trunks outgoing fro-1n the switch, a number of these are provided and each trunk, such as, the trimks 111 and 112, appears in its respective row 105, 106 of contacts. Each of these trunks, it will Serial No. 669,034.

be noted, occupies the complete vertical row of contacts and is accessible to all of the links in all of the horizontal groups.

For each vertical row of contacts there is provided a vertical operating bar which is arranged to be actuated by means of a vertical operating magnet. For instance, the bars individual to the vertical rows 103, 104, 105 and 106 are actuated by the associated operating magnets 113, 114, 115 and 116. In av similar manner, there is provided for each of the horizontal links, an operating bar. The bars 150, 151, 152 and 153 for the particular links shown are actuated by means of the horizontal operating magnets 125, 123, 138 and 137, respectively.

Briefly, the operation of the switch consists of energizing the vertical operating magnet for the vertical bar which is individual to the row of contacts in which the calling line appears. Also, the vertical magnet for the vertical bar which is individual to an idle outgoing trunk is energized. With there two bars in their actuated position, the next step is to energize the horizontal operating magnet which is individual to the horizontal bar associated with the first idle horizontal link in the proper group. This establishes the connection through the switch and the vertical operating magnets may now be released to restore their associated bars, the connection being maintained by the continued energization of the horizontal magnet and the continued operated condition of its associated horizontal bar. For a more complete understanding of the mechanical features of the switch, reference is made to the patent to C. L. Goodrum and J. N. Reynolds, No. 1,515,735, issued Nov. 18, 1924.

Due to the fact that the horizontal operating magnets are designed to actuate comparatively heavy parts they are necessarily more or less slow on releasing as compared with. the releasing times of a relay. This means that after a horizontal. bar has been put in use, to actuate the associated contacts, the bar must be restored to its normal position before it can again be taken for use to actuate other contacts in. the switch. Obviously, unless the bar is fully restored before the magnet is again energized, the operating mechanical parts will not be placed in the proper relative positions to insure a successful operation when the magnet is again energized. There is, therefore, an appreciable interval of time between the instant when the circuit of the horizontal magnet is opened and the instant when the associated bar is returned to the released position where it again may be successfully operated.

Since it is desirable to control the selection of the horizontal magnets by an ordinary start wire which leads over the front and back contacts of a chain of relays, such as the relays 124 and 126, it is desirable that some means be provided to prevent the reenergization of any horizontal magnet until it has fully restored its associated bar from a prior use. The manner in which thisv end is accomplished will now be discussed.

Assume that the subscriber of line 100 wishes to make a call. 011 initiating the call his line relay 118 operates over an obvious circuit. Relay 118 operates the relay 119 in a circuit through the winding of relay 119 and inner left contact of relay 120. Relay 119 operates both the relays 120 and 121. It will be noted that the relays 119, 120 and 121 constitute a set of group relays which are common to 'all of the horizontal links 107, 108, etc. The circuit for relay 120 leads through the right hand winding thereof to ground at the contact of relay 119. Th circuit for relay 121 leads through the right hand winding thereof, contact of relay 119 and thence over the common con ductor 139, back contact of relay 130 to ground at the contact of slow operating relay 133. Relay 121 locks in a circuit through its left-hand winding and left contact, conductor 1 10, inner left back contact of group relay 14:1, and winding of relay 130 to ground at the contact of relay 133. The relay 130 operates in the above traced circuit. Relay 121 causes the operation of relay 122. It will be observed that the relays 130, 131, 132 and 133 constitute a group of control relays which are common to all groups of lines in the switch 102. Relay 121, in operating, closes a holding circuit for relay 120 through the left-hand winding of said latter relay. When relay 120 operates it opens the circuit of relay 119 and this latter relay releases.

Relays 130 and 131 jointly cause the operation of relay 13 1. The circuit for this purpose leads through the normal contact of relay 133, front contact of relay 130, back contact of relay 131, outer left contact of relay 121, outer left contact of relay 120, left contact of relay 118, conductor 142, upper winding of relay 1341 to battery. Relay 13 1 prepares a locking circuit for itself which also causes the operation of relay 131 as follows: battery, through the lower winding and lower front contact of relay 13 1, winding of relay 131, front contact of relay 130 to ground. Relay 131, in operating, opens the original opera-ting circuit of relay 13a and also causes the operation of the vertical operating magnet 113 and one of the trunk vertical magnets. T1161 circuit for magnet 113 may be traced from ground, through contact of relay 133, left front contact of relay 130, left front contact of relay 131, upper contact of relay 13a and winding of magnet 113 to battery. Magnet 113 operates the associated vertical rod and prepares the contacts in the vertical row 103. Assuming that the first trunk 111 is busy and the second trunk 112 is idle, the vertical operating magnet 116 is operated in a circuit as follows: ground, through the right contact of relay 131, lowermost contact of relay 13a, inner lower front contact of relay (this relay being operated due to the busy condition of trunk 111), inner lower back contact of relay 136 and winding of magnet 116 to battery. Magnet 116 operates the associated rod and prepares the contacts in the vertical row 106.

\Vith both magnets 113 and 116 operated a circuit is closed for operating the horizontal magnet 123 associated with the horizontal link 108, which is assumed to be idle. This circuit may be traced from ground through the lower contact of magnet 116, lowermost contact of magnet 113, start conductor 1 13, left contact of relay 122, inner left back contact of relay 124, right hand winding of horizontal magnet 123 to battery. Magnet 123 operates the associated bar 151, resulting in the establishment of a connection between the incoming line 100 land the link 108 and between the link 108 and the outgoing trunk 112. As soon as the connection is established, a. holding circuit is prepared as follows for the magnet 123: battery, through both windings of said magnet, winding of the relay 124-, contacts of the switch 102, conduct-or 1 14;, to ground at the inner lower contact of magnet 116. The relay 12t does not operate in this circuit since it is shunted by the circuit above traced over the start conductor 1 13.

When the magnet 113 operates, as above described, it closes a circuit for the slow to operate relay 132 from ground at lower contact of magnet 116 through the inner con tact of magnet 113. Relay 132 in operating causes the operation of a second slow to operate relay 133. Atthe end of the interval measured by the operation of both of these relays, the holding ground is removed to permit the various relays above mentioned to release. In the first instance, the holding circuit of relay 130 and relay 121 is opened and these relays release. Also, the holding circuit of relay 131 and relay 134: is opened and these relays release. Relays 130 and 131 open the circuit for the vertical operating magnet 113, which releases. Relay 131 also causes the release of the vertic-a1 operating nragnet 116. lVith the vertical magnets 113 and 116 released, the con.- nection through the switch is held by the energization of the horizontal magnet 123. The circuit for this magnet extends as above traced to the test conductor 144, which has in the meantime been grounded from another source in the well known manner. The vertical operating magnet 113 in releasing opens the circuit of relay 132, which releases, and in turn releases the second slow relay 133.

Relay 121 in releasing causes the release of relay 122 and also the release of the group relay 120.

With the vertical operating magnets and the relay 122 released, the shunt around the winding of relay 124 is removed and this relay operates in series with the horizontal magnet 123. Relay 124 in operating extends the start circuit through to the contacts of the relay 126 relating to the next link in the group.

At the time ground is placed upon the test conductor 144 of the trunk 112, a circuit is closed for cut-off relay 117 as follows: battery, through the Winding of said relay, through contacts of the switch 102 to the grounded conductor 144. Relay 117 opens the circuit of the line relay 118 to prevent the reoperation of relay 134 unless some other line in the same vertical group is call- %Vhen magnet 116 releases: after the connection is established, relay 136 is operated to identify the trunk 112 as busy. The circuit for this relay leads from battery through its upper winding, inner upper back contact of magnet 116 to ground over conductor 144.

hen the connection is no longer required, ground is removed from the test conductor of the trunk 112 whereby the circuits of magnet 123, relay 124 and relay 117 are opened to permit them to release. The magnet 123 restores the switch and this disestablishes the connection.

It will now be assumed that some other line in the same horizontal group, such as the line 145, initiates a call at about the time the line is being disconnected. At the instant the ground potential is removed from the test conductor 144 of the trunk to which the line 100 is connected, the relay 124 being quick acting, releases immediately. On the other hand, the magnet 123 being comparatively slow, requires an interval to retract its armature 127 and permit the horizontal rod to restore to its full released position where it may be taken in use again. If at this instant the start wire 143 is permitted to be extended through the back contact of relay 124 by reason of the fact that the line 145 has just initiated a call, the magnet 123 may again be operated before it has succeeded in fully releasing. The result would be an improper operation of the switch. To

prevent this the magnet 123 is provided with a set of contacts 128 and 129. These contacts are closed when the magnet is operated and are so adjusted that they do not open until the magnet has fully released and fully restored the associated bar to normal. Consequently, when the line 145 initiates a call at the time the first connection is about to be released, the group relay 121 is operated and causes the operation of relay 122, as above explained. Instantly relay 122 operates, a substitute circuit is prepared for the magnet 123 and relay 124 to replace the circuit depending upon the ground potential of conductor 144, this potential having just been removed. This circuit may be traced from battery, through the winding of magnet 123, winding of relay 124, contacts 129 and 128 to ground at the contact of relay 122. Therefore, the relay 124, if it has just re leased, is immediately reoperated and the magnet 123 also discontinues its releasing action. lVith the relay 124 operated, the start wire 143 is extended through the front contact of said relay on to the contacts of the next relay 126 related to a succeeding horizontal link. lVhen, therefore, ground potential is later applied to the conductor 143 after the operation of the vertical magnets, no interference is caused with the horizontal magnet 123, but instead the succeeding horizontal magnet 125 in a fully released condition is operated.

Later, when the start wire is opened after the call has gone through successfully and relay 122 releases, the horizontal magnet 123 and relay 124 can be deenergized to disestablish the first connection.

WVhat is claimed is:

1. In combination, a switch having contact operating bars, a magnet for each of said bars for operating the same, a circuit extending to said magnets for operating any one thereof, and means to prevent the extension of the circuit to a magnet which has once been operated until such magnet has fully released the associated bar.

2. In combination, a switch having contact operating bars, individual magnets for each bar for operating the same, a start circuit common to all of the magnets for operating any one thereof, and means to prevent the extension of the start circuit to a particular magnet which has once been operated until such magnet has fully released the associated bar.

3. The combination in a coordinate switch having incoming lines, outgoing lines, intermediate links, and individual bars for said links, of magnets for operating said bars to establish a connection between an incoming line and an outgoing line by means of the corresponding link, a start circuit extending to said magnets for operating any one thereof, and means to prevent the extension of the start circuit to one of said magnets which has once been operated until such magnet has fully released the associated bar.

4. In combination a switch having contact operating bars, a magnet for each of said bars for operating the same, a start circuit for operating said magnets, relays each individual to one of said magnets for extending said start circuit, and means to prevent one of said relays from extending the start circuit to the associated magnet which has once been operated until such magnet has fully released the associated bar.

5. In combination, a switch having contact operating bars, operating magnets one for each of said bars, a start circuit for operating any one of said magnets, a set of spring contacts for each of said magnets, and means including said spring contacts to prevent the extension of said start circuit to one of said magnets which has been previously operated until such magnet has fully released the associated bar.

In witness whereof, I hereunto subscribe my name this 10th day of October A. 1)., 1923.

EDGAR I-I. CLARK. 

